Method of producing pyrophosphates



. Patented Dec. 18, 1934 UNITED STATES PATENT OFF This inventionrophosphates in production of acid sodium particularly to a process forby which certain are perfected phosphate is pro 1,984,968 ICE METHOD OFPYROPHO PRODUCING SPHATES Augustus -H. Fiske, Warren, and Charles S.

East Rumford Chemical Providence,

Works, Rumford, R. I., a

R. 1., assignors to corporation of Rhode Island No Drawing. ApplicationAugust 31, 1931,

Serial No. 560,510

1 Claim.

relates to the production of pygeneral and especially to thepyrophosphate, and producing the same economies in the manufacture andby which a high grade pyroduced well adapted for use in baking powdersor for like purposes as for leavening and wherever may be required.

Our procedure, be set forth in from undesirable per, arsenic, fluorine,etc., normal amount of iron and a pyrophosphate of any nature as well asWe employ in our process phosphoric acid free impurities such as, lead,copbut containing the aluminum (up to 2% approximately, calculated onthe basis of A1203 and F6203) This acid is preferably at about 50 to 55Baum or may be at even greater strength. Our usual solution will containabout 70% to 75% of orthophos phoric acid and while we do not wish tolimit our invention to these exact strengths, it-has phoric acid solutibeen our experience that phosons of about this strength give the bestresults in processing of the materials.

In explaining a characteristic procedure according to our invention wemay consider for an example our process as applied to the production ofacid sodium pyrophosphate as this material is commercially the phates.invention to the most common of the pyrophos- We do not wish, however,to limit our preparation of this pyrophosphate but make reservation thatthe process as described in this specification by us is applicable tothe manufacture of other pyrophosphates both acid and basic and neutraland containing a variety of bases-such as calcium, magnesium, and

potassium.

In our process anufacture of acid sodium phosphoric acid is thoroughlyas applied for example to the pyrophosphate, the mixed with thecalgredients in one operation.

This process may be carried out in an oven with a travelling hear thcontaining ploughs or stirphosphoric acid in place of the usual moredilute solutions.

The sodium hydroxide of soda ash 13 of great advantage both in procabout200 during the process of formation where melting at high temperature isreduced to a minimum and similarly discoloration from this source isminimized.

process and resulting What we therefore by Letters Patent is:

decrease in economy. claim and desire to secure a permanent dry formed.

. AUGUSTUS H. F'ISKE.

CHARLES S. BRYAN.

